NEW ORLEANS — The Louisiana Supreme Court has overturned a constitutional amendment barring felons from running for office because voters approved a version without a last-minute legislative change.

“Simply stated, what the citizens voted on was not what the legislature enacted,” Justice John L. Weimer wrote for the 6-1 majority in a lawsuit brought by former state Sen. Derrick Shepherd.

Voters had approved an amendment in 1997 forbidding convicted felons from running for office for 15 years after the end of their sentences. However, the version on the ballot omitted an amendment exempting those sentenced only to probation.

Shepherd was not allowed to run for the state House in 2015 because his federal sentence for conspiring to launder money had ended in 2014. He pleaded guilty in October 2008, signing a statement that he had laundered more than $140,000 for Gwendolyn Joseph Moyo in late 2006, making about $45,000 from the scheme. He was sentenced in October 2010 to three years and a month in prison, and, after getting out of prison, was on supervised release until May 2014.

In a statement emailed Wednesday by spokeswoman Danae Columbus, Shepherd said he was grateful for the justices’ decision and may run for Republican David Vitter’s U.S. Senate seat.

“My constituents are asking me to run and I am giving it full consideration,” he said.

In his dissent, Justice Greg G. Guidry said Shepherd’s lawsuit should have been thrown out because that exemption did not apply to him.

“The electorate and both the House and Senate were of a single mind that persons in the plaintiff’s position should be prohibited from seeking elective office,” Guidry wrote.

However, Weimer wrote, “our fidelity must be to the mandatory requirements of the constitution without regard to the parties, or to the wisdom and policy of the amendment at issue.”

Ignoring the procedures for changing the state constitution would open it to change without the protections in the constitution itself, he wrote. “We are thus duty-bound by the constitution to affirm the district court’s judgment holding the amendment was not properly enacted.”

Justice Scott J. Crichton said he agreed with the majority but wrote a separate opinion “to emphasize that, like the vast majority of the citizens of the state of Louisiana, I believe that convicted felons should be disqualified from the electoral process.”

He added, “The Legislature can, if it chooses to do so, once again address this issue in order to rectify this troublesome result.”

“Louisiana voters clearly supported prohibiting felons from qualifying and holding public office. It is unfortunate that unexplained administrative errors rendered this constitutional prohibition invalid,” Attorney General Jeff Landry said in a statement late Wednesday. “I hope the Governor includes this in the call for a special session so the matter can be resolved as quickly as possible. In the meantime, I trust that the voters will not elect convicted felons.”